Copper alloy



Patented, Apr. 2, 1940 UNiTED STATES COPPER ALLOY Horace F. Silliman, Waterbury, Conm, asaignor 1 to The American Brass Company, Waterbury,

Conn a corporation of Connecticut No Drawing.

Application August 19, 1938, Serial No. 225.773

50mins. (01. 15-154) m l My invention relates to alloys of copper and more particularly to the alloys of copper and tin, commonly called bronzes. v

The object of my invention is to provide improved copper-tin alloys.

Several alloys of copper containing tin, andsometimes other elements, are commonly used in the arts. These are among the most useful of all copper alloys, because of their high strength,

high wear resistance, and high fatigue resistance.

It has been known for many years that coppertin'alloys containing a small amount of phosphorus are stronger and more ductile than the corresponding copper-tin alloys without phos- 16 phorus. In wrought-alloys the phosphorus con tent may vary from a trace to about 0.50%. In castings the phosphorus content may be even higher.

While phosphorus additions improve the me- 20 chanical properties of copper-tin alloys, they have certain disadvantages. First, the phosphorus (as is well known) lowers the electrical conductivity. As high a conductivity as possibleis desirable in. current-carrying springs for which 5 phosphor bronzes are commonly used. Secondly,

the phosphorus. because of the low melting point of the phosphide eutectic, is one of the factors contributing to the hot shortness of phosphor bronze.

When boron is substituted for the phosphorus in phosphor bronzes, I have-found that all the advantages -01 the known phosphorus-bearing copper-tin alloys are obtained with the additional advantages of higher electrical conductivity and freedom from hot shortness. The use of boron instead of phosphorus does not change appreciably the tensile strength or hardness of the corresponding alloys.

In practicing my invention I alloy'the metals 40 (and scrap if used) in the usual manner and add to the melt the boron either in the form of a boron alloy or as the element. At present I prefer to use 2% to 5% boron-copper alloy as a source of boron. I also may add the boron by any of 45 the methods given in mycopending application for a Process for producing boron-copper alloys, Serial No. 188,471. The melt is then poured into a suitable mold. If the alloy is to be finished in wrought forms, the casting is rolled, drawn, 50 swaged, extruded, forged, or worked in any manner to forms such as sheet.-rod, wire, tubes, forgings, and profiles. The presence of boron makes it possible to. perform these operations hot, if desired. 55 The amount ofboron added may vary from a trace up' to 1%, and more, but above about 1% there appears to be insufficient improvement to justify the added cost. The exact percentage will be determined by the effect required. For example, with 10% tin, .05% of boron is sumcient to deoxidize the alloy but better results are obtained in hot rolling ii sufllcient boron is added so that at least 0.1% boron-is presentin the resultant alloy.

i It is not necessary to limit the composition of 10 the improved alloys to copper, tin, and boron. I

- may substitute for equivalent quantities of copper and tin such elements as zinc, lead, manganese, iron,- magnesium, titanium, vanadium-and zirconium. I am aware of U. S. Patent 2,116,252 to Schwarzkopf disclosing the use of boron. in copper-cadmium alloys, and do not wish to include cadmium in these alloys. My alloys are hot work'- time while copper alloys containing more than about 1% cadmium are diflicult to hot work. Some of the combinations, such as copper-tintitanium-boron, copper-tin-vanadium-boron, and copper-tin-zirconium-boron, respond to precipitation hardening heat treatments. The useful ranges of the elements which may be added to copper base copperetin-boron alloys are:

Per cent Zine 0 to 45 Lead 0 to 5 Manganese 0 to 10 Magnesium Mo 3 Ir 0 to 10 Titan 0 to 10 Vanadium 0 to 10 Not more than 0.5% lead will be tolerated if 85 hot working methods 'are used. but the other elements listed above do not interfere.

For this alloy the tin content should be at least 0.1%. For wrought alloys, particularly 'where 40 some cold working may be necessary, the tin content will be less than 12%. "Sometimes, how-' ever, for castings used' as such, the tin may be as high as 20% by weight. Up to 20% tin does not injure the hot working properties, however. 4,5 Whatever the alloy may contain beside copper, tin, and boron, the copper predominates, and except in the'case of alloys containing the higher amounts of zinc is at least 70%. An alloy which. is preferred because it combines good ductility, high strength and high fatigue resistance with ease of working comprises 4% to 11% tin, 0.05% to 0.5% boron, and balance copper.

The boron also improves the copper-tin alloys in several other ways. For example, the grain formed. Furthermore, the presence of the'boron in the alloy modifies the scale resulting from annealing in air, so that the pickling operations are easier and less costly.

The presence 01' boron also improves the resistance of the copper-tin alloys to arcing when such alloys are used as contacts to make and break electrical circuits. The alloy with about 8% oitin is particularly adapted to this purpose because of its inherently good strength and resistance to mechanical wear.

My alloy may be used with increased'advantages for any of the purposes for which the corresponding alloys containing phosphorus are used such as springs, bridge plates, and various other articles, as it has improved spring qualities and greater wear resistance. It is well adapted for I use as welding rod and brazing, or hard solder,

and is much better than the phosphor bronzes for these uses.

. Having thus set forth the nature of my invention, what I claim is:, v

1. A hot-workable copper-base alloy comprising 0.1% to 20% tin, .05% to 50% boron, balance substantially all copper. the boron being in solution with the tin in. the copper.

2. A copper-base alloy which can be hot worked and cold worked comprising .05% to 50% boron, 4% to 11% tin, balance copper, the boron being in solution with the tin in the copper.

3. A copper-base alloy comprising 0.1% to 20% tin, 0.01% to 1% boron and balance substantially all copper, at least part of the boron being in solution with the tin in the copper.

4. A copper-base alloy comprising 0.1% to 20% tin, but which is free from cadmium, boron with- -in the range of 0.01% to 1%, and balance substantiallyall copper, and which is characterized by improved welding properties and improved electrical conductivity overi-the same alloy without boron and also the same alloy with phos phorus, and with amounts of other elements insufficient to affect the characteristics named.

5. A hot workable copper-base alloy comprising 0.1% to 20% tin, 0.01% to 1% boron at least a part of which is in solution with the tin in the copper, and balance substantially all copper, which alloy is characterized by improved welding, casting and brazing properties, by improved electrical conductivity, smaller grain size, and modified scale resulting from annealing in air which is more easily removed, over the same alloy without the boron, and with amounts of other elements insufllcient to aiiect the characteristics named.

HORACP F. SILLIMAN. 

